Display apparatus with a touch-sensitive layer and an antireflection lattice

ABSTRACT

Abstract of the Disclosure A display apparatus having a display layer ( 2 ) and a touch-sensitive layer ( 3 ) running parallel thereto. An antireflection lattice is provided which is arranged on the touch-sensitive layer ( 3 ), the lattice elements being able to move toward one another or having a touch sensitivity which is independent of other lattice elements.

RELATED APPLICATIONS

This is a U.S. national stage of application No. PCT/DE2003/002727,filed on 13 Aug. 2003.

This patent application claims the priority of German patent applicationno. 102 37 119.9 filed 13 Aug. 2002, the disclosure content of which ishereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a display apparatus having a display layer anda touch-sensitive layer running parallel thereto.

BACKGROUND OF THE INVENTION

Such display apparatuses are used when it is necessary not only todisplay information graphically but also to use the apparatus for input.Such a display apparatus is useful particularly when using graphicaluser interfaces for operating systems or application programs. In thesecases, functions are activated by buttons, in which case either thebuttons can be clicked on with a cursor, for example using a mouse, orelse the appropriate function can be activated by touching the displayapparatus directly. Such display apparatuses are often calledtouchscreens.

Since such display apparatuses are able to save an input unit, displayapparatuses of this kind are used in preference for small portableappliances, for example “handhelds” or PDAs. Particularly in mobileoperation, however, the problem arises that there is a relatively highlevel of ambient brightness, and reflections appear on the displayapparatus which significantly impair the legibility of the displayapparatus.

From cathode ray tube units, where the problem of reflection likewisearises, it is known practice, in order to avoid reflections on thescreen surface, to arrange a lattice in front of the screen, thisusually being a fine-meshed wire netting, and this means that althoughdisplayed information can still be easily seen by an observer, obliquelyincident ambient light can no longer cause any reflections.

In touch-sensitive display apparatuses, such wire netting or a similarapparatus cannot be used, because the relatively rigid structure meansthat even touching it with a relatively pointed object such as a penwould result in a broad pressure area, which can result in incorrectinputs. Even when the touch-sensitive layer has a high resolution,precise work is no longer possible.

Another known possibility for avoiding disruptive reflections is toroughen the surface pointing in the direction of an observer by startingto etch it, for example. A drawback of this solution is that the scattereffect does not just affect incident ambient light, but rather likewiseaffects the light which individual pixels on the display layer emit andscatter, and hence the sharpness of the image is reduced.

SUMMARY OF THE INVENTION

One object of the invention is to provide a display apparatus which hasa touch-sensitive layer and which nevertheless has protection againstsurface reflections from ambient light.

This and other objects are attained in accordance with one aspect of thepresent invention directed to a display apparatus having a display layerand a touch-sensitive layer running parallel thereto. The side of thetouch-sensitive layer which is remote from the display layer has anantireflection lattice comprising lattice elements which can move towardone another.

Another aspect of the present invention is directed to a displayapparatus having a display layer and a touch-sensitive layer runningparallel thereto. That surface of the touch-sensitive layer which isremote from the display layer has a lattice-like surface texturing, thelattice spacing being matched to the pixel spacing on the display layersuch that the ratio of the lattice spacing to the pixel spacing iswhole-numbered.

The whole-numbered ratio of the lattice spacing to the pixel spacingensures that the light emitted by pixels on the display layer is notscattered, but rather reaches the observer directly. The lattice formsmore or less microscopic channels. Obliquely incident light, on theother hand, is reflected or absorbed by the lattice elements.

Yet another aspect of the present invention is directed to a displayapparatus having a display layer and a touch-sensitive layer runningparallel thereto. The touch-sensitive layer contains lattice elements,the lattice spacing being matched to the pixel spacing on the displaylayer such that the ratio of the lattice spacing to the pixel spacing iswhole-numbered.

In the case of such an embodiment, the lattice elements which preventreflections have already been integrated into the touch-sensitive layer.

Still another aspect of the present invention is directed to a displayapparatus comprising a display layer and a touch-sensitive layer runningparallel thereto, wherein the touch-sensitive layer comprises strip-likelattice elements arranged in lattice form, and touch sensors integratedinto nodes of the lattice. In such an embodiment, the touch-sensitivecomponents and the antireflection components need not be separate units,but rather the same elements can perform functions both for avoidingreflections and for producing the touch sensitivity.

In a display apparatus of the type mentioned at the outset, it isadvantageous if the lattice elements are of strip-like design, thelattice elements being able to move toward one another at nodes of thelattice. The strip-like configuration ensures a good antireflectionbehavior.

It is particularly advantageous if the angle between the latticeelements and the touch-sensitive layer is adjustable. The latticeelements mean that the viewing direction parallel to the latticeelements is highly preferable to an oblique viewing angle. A changeableangle between the lattice elements and the touch-sensitive layer allowsthe preferred viewing direction to be adjusted in line with the user'swishes.

Another advantageous configuration of the first solution provides forthe antireflection lattice to be removable. In the case of the thirdsolution mentioned, where the touch-sensitive layer contains latticeelements, it is advantageous for the lattice elements to have liquidcrystals. This means that the antireflective behavior can be turned offand turned on when necessary.

The latter solution advantageously provides for electrical conductorsrunning parallel to the display layer to be integrated into the latticeelements and for the lattice elements to be made of an elastic material,with means being provided for evaluating capacitive, inductive orresistive characteristic values for two electrical conductors fromdifferent lattice elements.

Further advantageous configurations of the invention are specified inthe subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a PDA with a display apparatus based on the invention,

FIG. 2 shows a schematic illustration of a first exemplary embodiment ofa display apparatus based on the invention,

FIG. 3 shows a three-dimensional illustration of lattice elements fromthe exemplary embodiment in FIG. 2,

FIGS. 4 to 6 show variants of the embodiment of lattice elements,

FIG. 7 shows a further exemplary embodiment with the touch-sensitiveproperties integrated into the lattice elements,

FIG. 8 shows a display apparatus based on the invention with a removableantireflection lattice,

FIG. 9 shows the arrangement from FIG. 8 with a removable antireflectionlattice,

FIG. 10 shows a display apparatus based on the invention withcontrollable lattice elements.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a PDA (Personal Digital Assistant) 11 with a displayapparatus 1 based on the invention. The display apparatus 1 is oftouch-sensitive design and, to this end, has a touch-sensitive layer 3.In the symbolic illustration in FIG. 1, there is also an antireflectionlattice 4 which is suitable for eliminating disruptive reflections.

FIG. 2 shows the display apparatus from FIG. 1 in a more detailedillustration. As can be seen from FIG. 2, the antireflection lattice 4comprises a multiplicity of lattice elements 5. These are at apredetermined angle 9 on a touch-sensitive layer 3. Preferably, theangle 9 is 90°. The lattice elements 5 form microscopic channels 10through which an observer looks onto the touch-sensitive layer and ontothe display layer 2 underneath. The display layer includes an array ofpixels 8. In order for good visibility to be ensured, the latticeelements 5 are thus oriented parallel to the viewing direction 12.Incident light 18 from the side is absorbed by the lattice elements 5and as a result only a small proportion thereof reaches the at leastpartially reflective surface of the touch-sensitive layer 3 or of thedisplay layer 2.

Particularly in the case of small portable appliances such as the PDAsshown in FIG. 1, it is easy to hold the appliance respectively such thatthe viewing direction is at right angles to the display apparatus 1. Inthe case of larger appliances such as

Particularly in the case of small portable appliances such as the PDAsshown in FIG. 1, it is easy to hold the appliance respectively such thatthe viewing direction is at right angles to the display apparatus 1. Inthe case of larger appliances such as Notebooks or permanently installedflat screens, however, it is not always possible or not always easy toorient the display apparatus 1 with respect to the user in optimumfashion. It is therefore advantageous if the lattice elements 5 are notrigid but rather are able to move such that their angle 9 with respectto the touch-sensitive layer 3 can be altered. This can be achieved, forexample, by the use of strip-like lattice elements 5 with slots at thelattice nodes 13, such that the strip-like lattice elements 5 running inone direction of the lattice are not connected to the strip-like latticeelements 5 running orthogonal to them. In the case of an embodiment withan adjustable angle for the lattice elements, optimum orientation can beachieved by means of user setting or automatically on the basis of theincident ambient light. To this end, by way of example, a sensor may beprovided which measures the angle of incidence of ambient light and usesappropriate control apparatuses to actuate the lattice elements 5 suchthat they are at an optimum angle.

The lattice elements 5 are either partially transparent ornontransparent. To attain a satisfactory action, the material of thelattice elements 5 should be light-absorbent or should form alight-absorbent surface. The lattice elements 5 could, for example, bemade of some conductive polymer material, which can be printed directlyon the surface of the touch-sensitive layer 3.

For the quality of the display apparatus 1, it is necessary for thelattice spacing between lattice elements 5 to be matched to the pixelspacing of the pixel elements 8 on the display layer 2. Otherwise, the“Moiré effect” may arise. This occurs when fractional-numbered spacingratios mean that lattice elements 5 are situated above pixel elements 8in particular regions, while in other regions the lattice elements 5 aresituated precisely between two pixels. The Moir é effect can be avoidedif the ratio of lattice spacing to pixel spacing is whole-numbered. InFIG. 2, the lattice spacing has been chosen such that it is twice thesize of the pixel spacing. Two pixels 8 therefore have one latticeelement 5.

FIG. 3 shows a three-dimensional schematic illustration of thearrangement of the lattice elements 5. The slots in the strip-likelattice elements 5 at lattice nodes 13 ensure that the lattice elementsare flexible with respect to one another. This is important so thatpressure on the lattice elements 5 is respectively transferred to theunderlying location on the touch-sensitive layer 3.

FIGS. 4 to 6 show alternative configurations of the antireflectionlattice 4. In the illustration in FIG. 4, studs are provided at thelattice nodes 13. This stud-like configuration ensures a very beneficialtransfer of force to the touch-sensitive layer 3. If the studs are of anappropriate size and the lattice spacing is correspondingly small, anadequate antireflection action can be produced. For example, the heightof the studs can be comparable to the lattice spacing.

In FIG. 5, there are likewise strip-like lattice elements 5, these beinginterrupted completely at the nodes 13. The width of the strips 5 can bereduced further, and hence it is not necessary for the strips to extendover the entire length between two nodes 13.

In the illustration in FIG. 6, there are bristle-like lattice elements7. Such an embodiment of the lattice elements is suitable, above all,when the ratio of the lattice spacing to the pixel spacing is muchgreater than 1. In one configuration of lattice elements, in which onlythe lattice nodes 13 permit a touch to be detected, the resolution ofthe touch-sensitive layer 3 would therefore be very low. However, sinceeach bristle is able to transfer a force exerted on it from above, it ispossible to attain a good touch resolution even with a large latticespacing.

In the embodiment in FIG. 7, the functions of the touch-sensitive layer3 and of the antireflection lattice 4 have been combined with oneanother. This is achieved by virtue of the lattice element 15 not onlybeing of strip-like design, in order to develop an antireflectionaction, but rather also being touch-sensitive. This is achieved byvirtue of the lattice elements 15 containing electrical conductors 14which do not touch at the nodes 13 (this cannot be seen in FIG. 7). Thespecific evaluation of individual electrical conductors 14 means that itis possible to evaluate a change in the spacing between two electricalconductors 14 at individual nodes 13. This is because a change resultsin capacitive, inductive or resistive values changing. To this end, thelattice elements 15 need to be elastic so that the exertion of apressure also results in a change in the spacing between two conductors.

Another possible way of combining the antireflection function and thetouch sensor function is to use lattice elements such as those shown inFIG. 5, for example, and additionally to set up touch sensors at thenodes. This can be done merely by using a capacitively sensitive sensorelement, for example, which is respectively arranged at a node 13.Capacitive sensor elements work by virtue of an object brought closealtering the electrical field, which results in a change of capacitancefor an electrode which represents the sensor element. This change ofcapacitance can now be evaluated.

FIG. 8 shows the possible way of connecting the antireflection lattice 4pivotably to a housing which holds the touch-sensitive layer 3 and thedisplay layer 2. In this way, the display apparatus can also be usedwithout an antireflection lattice 4.

FIG. 9 shows a similar configuration to that in FIG. 8, but thereflection lattice 4 can be mounted instead of being arranged pivotablyon the housing. Positioning pins 16 ensure that the antireflectionlattice is positioned such that the lattice elements do not disturb thelight radiated by pixel elements on the display layer 2.

FIG. 10 shows an embodiment of a display apparatus based on theinvention in which lattice structures have been incorporated into thetouch-sensitive layer 3, for example through etching a grid structureinto the touch-sensitive layer or doping the material used for thetouch-sensitive layer 3. In this case, the lattice elements do not needto be flexible. The lattice elements may also be formed from liquidcrystals or an electrochromic material contained in the touch-sensitivelayer 3. In this case, the lattice elements can be turned on or off asrequired by applying an electrical field in the area of forming thelattice elements, e.g., by applying a conductive surface coating actingas electrodes on each side of the touch-sensitive layer 3 and applyingan electrical charge to these electrodes. The applied electrical fieldresults in a change of the optical properties of the electrochromicmaterial, for example by changing from a transparent to an absorbingstate. So as not to impede the display properties of the display layer,the lattice spacing should also be matched to the pixel spacing in thiscase.

When liquid crystal antireflection lattices are used, the opticalorientation of the lattice elements can be adjusted by changing theorientation of the electrical field used to activate the liquidcrystals, for example through rearranging the electrodes used togenerate this field. In this case, the adjustment can be made eithermanually by the user or automatically on the basis of the level and/orangle of incident ambient light.

The scope of protection of the invention is not limited to the examplesgiven hereinabove. The invention is embodied in each novelcharacteristic and each combination of characteristics, which includesevery combination of any features which are stated in the claims, evenif this combination of features is not explicitly stated in the claims.

1. A display apparatus comprising: a display layer; a plurality of pixelelements arranged on the display layer; and a touch-sensitive layerrunning parallel to the display layer; wherein a side of thetouch-sensitive layer which is remote from the display layer includes anantireflection lattice comprising first lattice elements extending in afirst direction parallel to the display layer and second latticeelements extending in a second direction parallel to the display layerand orthogonal to the first direction, the first and second latticeelements intersecting at nodes of the lattice at which the first andsecond lattice elements can move with respect to one another, the firstand second lattice elements forming a plurality of microscopic channelsextending in a third direction orthogonal to the first and seconddirections, the plurality of channels being associated with theplurality of pixel elements for viewing the display layer in the thirddirection and absorbing or reflecting oblique incident light from thefirst or second directions.
 2. The display apparatus as claimed in claim1, wherein the first and second lattice elements are of strip-likedesign comprising slots at the nodes of the lattice, such that the firstand second lattice elements are able to move with respect to one anotherat the nodes of the lattice.
 3. The display apparatus as claimed inclaim 1, wherein the first and second lattice elements are ofbristle-like design.
 4. The display apparatus as claimed in claim 1,wherein the lattice spacing is matched to a pixel spacing on the displaylayer such that the ratio of the lattice spacing to the pixel spacing iswhole-numbered.
 5. The display apparatus as claimed in claim 1, whereinan angle between the first and second lattice elements and thetouch-sensitive layer is adjustable.
 6. The display apparatus as claimedin claim 5, further comprising means for automatically adjusting theangle on the basis of the angle of incident ambient light.
 7. Thedisplay apparatus as claimed in claim 1, wherein the first and secondlattice elements comprise a light-absorbent material.
 8. The displayapparatus as claimed in claim 1, wherein the antireflection lattice isremovable.
 9. A display apparatus comprising: a display layer; aplurality of pixel elements arranged on the display layer; and atouch-sensitive layer running parallel the display layer; wherein thetouch-sensitive layer comprises first lattice elements extending in afirst direction parallel to the display layer and second latticeelements extending in a second direction parallel to the display layerand orthogonal to the first direction, the first and second latticeelements intersecting at nodes of the lattice at which the first andsecond lattice elements can move with respect to one another, the firstand second lattice elements forming a plurality of microscopic channelsin the touch-sensitive layer extending in a third direction orthogonalto the first and second directions, the plurality of channels beingassociated with the plurality of pixel elements for viewing the displaylayer in the third direction and absorbing or reflecting obliqueincident light from the first or second directions, the lattice spacingbeing matched to a pixel spacing on the display layer such that theratio of the lattice spacing to the pixel spacing is whole-numbered. 10.The display apparatus as claimed in claim 9, wherein the first andsecond lattice elements are made of liquid crystals disposed in thetouch-sensitive layer.
 11. The display apparatus as claimed in claim 9,wherein the first and second lattice elements comprise an electrochromicmaterial.
 12. The display apparatus as claimed in claim 10, furthercomprising: means for automatically adjusting the optical properties ofthe first and second lattice elements on the basis of the ambient lightconditions.
 13. A display apparatus comprising: a display layer; and atouch-sensitive layer running parallel to the display layer; wherein thetouch-sensitive layer comprises strip-like lattice elements arranged inlattice form, and touch sensors integrated into nodes of the lattice;wherein the lattice elements comprise electrical conductors which runparallel to the display layer and do not touch at the nodes of thelattice, and the lattice elements comprise an elastic material, andmeans for evaluating the spacing of the conductors at nodes of thelattice.
 14. The display apparatus as claimed in claim 13, wherein thetouch sensors are capacitive sensor elements.
 15. The display apparatusas claimed in claim 1, wherein the first and second lattice elements areof strip-like design interrupted completely at nodes of the lattice suchthat the first and second lattice elements are able to move with respectto one another at the nodes of the lattice.
 16. A display apparatuscomprising: a display layer; a plurality of pixel elements arranged onthe display layer; a touch-sensitive layer running parallel to thedisplay layer; and a further layer; comprising an antireflection latticecomprising first lattice elements extending in a first directionparallel to the display layer and second lattice elements extending in asecond direction parallel to the display layer and orthogonal to thefirst direction, the first and second lattice elements intersecting atnodes of the lattice at which the first and second lattice elementswhich can move with respect to one another, the first and second latticeelements forming a plurality of microscopic channels in thetouch-sensitive layer extending in a third direction orthogonal to thefirst and second directions, the plurality of channels being associatedwith the plurality of pixel elements for viewing the display layer inthe third direction and absorbing or reflecting oblique incident lightfrom the first or second directions, the further layer being mounted ontop of the touch-sensitive layer on a side which is remote from thedisplay layer and is separate from the touch-sensitive layer.